Set Appliance State:

Gas Off
Isolate Mains Power to appliance as per TOPs P4
Turn Hot Water Tap On
Attach pressure tube to positive connection on FGA
Attach FGA tester to gas valve outlet pressure test point
Remove the left hand side panel if required
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Measurement:

Reset appliance if required (press reset button once then release)
With the fan running measure the fan pressure.
The reading will be negative.
The pressure measured should read greater than -3.5 mb (e.g. -4mb)
Note:
When pressure gauge is removed the pressure test point
should be tightened and checked for gas tightness.